Re: 50 Watt idle power regression bisected to Linux-3.10

[Mike Galbraith <bitbucket@online.de>]

On Wed, 2013-12-11 at 20:49 -0800, H. Peter Anvin wrote: 
> On 12/11/2013 08:25 PM, Mike Galbraith wrote:
> >  arch/x86/include/asm/mwait.h   |    4 ++--
> >  arch/x86/kernel/cpu/common.c   |    7 ++++---
> >  arch/x86/kernel/setup_percpu.c |    1 +
> >  3 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > Index: linux-2.6/arch/x86/kernel/cpu/common.c
> > ===================================================================
> > --- linux-2.6.orig/arch/x86/kernel/cpu/common.c
> > +++ linux-2.6/arch/x86/kernel/cpu/common.c
> > @@ -65,13 +65,14 @@ void __init setup_cpu_local_masks(void)
> >  }
> >  
> >  /* allocate percpu area for mwait doorbell */
> > -char __percpu *mwait_doorbell;
> > +DEFINE_PER_CPU(char *, mwait_doorbell);
> > +EXPORT_PER_CPU_SYMBOL(mwait_doorbell);
> >  
> 
> Sorry, this is wrong.  This is NOT a percpu variable, it is a pointer to
> a percpu allocation, but the variable itself is not a percpu variable.
> This explains your boom.

Yeah, I know, I already slapped myself upside the head.

(what were you thinking mikie...la la la la la:)

-Mike